Analysis of cadmium-based pigments with time-resolved photoluminescence

Abstract

For the first time the kinetic emission properties of commercially available cadmium-based pigments were studied. For analysis, a streak camera-based photoluminescence device was used with a temporal resolution ranging from ps to μs, considering the emission from both the band edge and the first deep trap state. Band edge emission shows a rapid picosecond lifetime strictly related to pigment composition, with cadmium sulphide pigments decaying more rapidly than those based on cadmium sulphoselenides. The trap state emission lifetime is on the order of tens of microseconds and is uncorrelated with pigment composition. In addition, a high dependence of spectral and lifetime emission properties on excitation irradiance has been observed, as carrier recombination in cadmium pigments is highly influenced by electron trapping. All this information provides insight into the photo-physical properties of these widely employed modern pigments, which highlights how luminescence measurements are useful for discriminating among cadmium pigments.